1. Earth Layers

2. Seismic Waves Scientists know that the Earth consists of layers
●this is known by studying seismic waves
●if the Earth was not layered, seismic waves would travel straight through at constant speed…
●this is NOT the case

3. Earth Layers Four Major Layers
1.) Crust – the thin, cool, rocky outer layer
●two types – Continental and Oceanic
Thick (40km)
Old (up to 4 byo)
Thin (7km)
Young (less than 180 myo)

4. Mantle
2.) Mantle –
●Upper mantle is similar to the crust (mostly solid rock)
●Lower mantle is warm and soft
●magma rises and lowers, creating convection currents

5. The Core 3.) Outer Core ● Hot and Liquid
Flowing iron produces Earth’s magnetic field
4.) Inner Core
● Hottest layer
SOLID iron-nickel
sphere
Solid due to immense pressure

6. Lithosphere & Asthenosphere
● cool solid outer layer of Earth
►consists of crust and uppermost mantle
Asthenosphere
● warm, soft and weak layer of Earth
►consists of the lower mantle

7. Moho Mohorovicic Discontinuity
● The separation between the crust and the mantle
● Shortened to Moho
● Discovered in 1909 by seismologist Andrija Mohorovicic
● Discovered it by studying seismic waves